JPH06277182A - Optometric apparatus - Google Patents

Abstract

PURPOSE:To avoid the influence on the accuracy of measurement even if there exists blurring by making an optical system wherein the front eye part of the eye to be examined is projected on a TV photographing means for observation and measurement to be a telecentric optical system. CONSTITUTION:A reflective image of a ring-like light source 5 by the cornea EC of an eye E to be examined is focused on a two dimensional light sensor 4 through an objective lens 1, an optically dividing member 2 and a diaphragm 3 and the dimension is measured to obtain a carvature radius of the cornea EC. On the other hand, an alignment sight target 7 is irradiated by means of a visible light source 6 and is photographed by means of a television camera 10 through lenses 8 and 9. An image Pi of the iris, an image Pr of the ring-like light source 5, an image Pa of the alignment sight target 7, an image PP of the pupil and a light source PS for illuminating the outer eye are displayed on a television monitor 11. As the optical system to the television camera 10 is made to be a telecentric system, even when there exists diffusion, there is no possibility to give influence on the accuracy of reading measurement. While the television monitor 11 is watched, when at first, a ring image P is well focused to the image Pa, of the sight target and a measurement button is pushed, the light sources 5 and 6 are turned off and the iris, namely the diameter of the cornea can be measured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optometry apparatus which is used in an ophthalmology clinic or the like and which performs optical measurement on an eye to be examined.

[0002]

2. Description of the Related Art In a conventional device under test, a measuring optical system and an anterior segment observation optical system for alignment are separately provided.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide an optometry apparatus in which the measurement optical system and the observation optical system are the same, and the measurement accuracy is not affected by blur.

[0004]

An optometry apparatus according to the present invention for achieving the above object comprises an illumination light source for observing the anterior segment of an eye and a predetermined illuminant for observing the anterior segment and the eye. It is characterized in that it has a television photographing means for performing measurement and an optical system for projecting an anterior segment image on the television photographing means, and the optical system is a telecentric system.

[0005]

In the optometry apparatus having the above structure, the anterior segment of the eye to be examined is photographed by the television photographing means via the telecentric optical system.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail based on the illustrated embodiments. FIG. 1 is an optical configuration diagram. In front of the eye E to be inspected, the objective lens 1 is sequentially arranged along the optical axis O1 from the eye E side to be inspected.
The light splitting member 2, the diaphragm 3, and the two-dimensional photosensor 4 are arranged,
A ring-shaped light source 5 is arranged around the objective lens 1. Furthermore, an optical axis that is orthogonal to the optical axis O1 and passes through the light splitting member 2.
A light source 6, an alignment target 7, a lens 8, a light splitting member 2, a lens 9, and a television camera 10 are sequentially arranged on O2, and the output of the television camera 10 is connected to a television monitor 11. The objective lens 1 and the lens 9 from the eye E to be examined to the television camera 10 are of a telecentric system.

A reflected image of the cornea Ec of the eye E to be inspected of the ring-shaped light source 5 is formed on the two-dimensional optical sensor 4 through the objective lens 1, the light splitting member 2 and the diaphragm 3, and its size will be described later. The radius of curvature of the cornea Ec can be obtained by measuring with a means. On the other hand, as shown in FIG. 2A, the anterior segment image of the subject's eye E is displayed on the television monitor 11 by the television camera 10, and the anterior segment is illuminated by an external eye illumination light source of visible light (not shown). ing. The alignment target 7 is the visible light source 6
Is illuminated by the television camera 1 through the lenses 8 and 9.
It is filmed at 0. An iris image Pi, an image Pr of the ring-shaped light source 5, an image Pa of the alignment target 7, a pupil image Pp, and an external eye illumination light source image Ps are displayed on the television monitor 11 in FIG. 2 (a). Since the optical system reaching the television camera 10 in this case is a telecentric system, even if there is a blur, it does not affect the reading measurement accuracy.

When the video signal of the scanning line 1 is shown in FIG. 2 (b), the sclera Es has strong reflection and the iris Ei is dark and has a low level. The signal can be binarized by setting the level L in the middle, and the size of the iris image Pi can be found by finding the distance between the intersections a and b by means described later. The scanning line 1 is off the center of the eye E to avoid the light source image Ps, and can be converted into the diameter of the iris image Pi if the amount of deviation is determined in advance.

FIG. 3 shows an electrical block circuit configuration diagram.
First, the measurement unit of the radius of curvature of the cornea will be described. The analog signal read from the two-dimensional optical sensor 4 is amplified by the amplifier 20 and the signal level is temporarily held by the sample value hold circuit 21. The digital signal is converted by the A / D converter 22. The optical sensor 4 is controlled by the clock signal of the driver 23. A
The digital signal output from the / D converter 22 is passed through the interface 24 and RAM (Random Access Memory).
25. Reference numeral 26 is a ROM (Read Only Memory) in which a control program for operating the microprocessor 27 is written. The ring image position formed on the two-dimensional optical sensor 4 is obtained from the data in the RAM 25,
The radius of curvature of the cornea is obtained by fitting it to a general formula such as an ellipse, displayed on the result display 28, and output to the printer 29 as necessary.

Next, the corneal diameter measuring section will be described. The video signal of the anterior ocular segment image of the subject's eye E captured by the television camera 10 is supplied to the television monitor 11 and the amplifier 30.
It is input to the cycle separation circuit 31, and the scanning line counter 32 is operated. The output c from the scanning line counter 32 is connected to the interface 24. The video signal amplified by the amplifier 30 is input to the comparators 34 and 35 and the sample value hold circuit 36, and the comparator 35
Is output to the sample value hold circuit 36 via the monostable multivibrator 37. Comparator 3
The other input of 5 is connected to the pupil level setting signal d, its output e drives the monostable multivibrator 37, and its output f is its sample value hold circuit 3
Then, the output voltage h is added to the predetermined voltage signal g via the adder 38 and the output signal h is connected to the input terminal of the comparator 34. The output i of the comparator 34 is connected to the gate input of the counter 39, and count control is performed by the clock output j of the oscillator 40. The count output k of the counter 39 is input to the interface 24, and the control signal m of the counter 39 is sent from the interface 24 to the counter 39. Further, the ring-shaped light source 5 and the light source 6 are connected to the interface 24, and the turning on / off control is performed.

The operation of the corneal diameter measuring unit will be described with reference to FIG. 4. Since the pupil image Pp is close to a black level and there is no individual difference, the pupil level setting signal d may be constant. If the monostable multivibrator 37 is driven by the fall of the output signal e from the comparator 35 and the video signal at the time of the fall of the signal e is held as a sample value, the level Li of the iris image Pi is determined and the individual difference Can be suppressed. A predetermined level g is added to this level Li, and the level h and the output signal of the TV camera 10 are compared by the comparator 34.
The iris signal i can be extracted by comparing with. The signal h from the adder 38 is output for each scanning line while the pupil of the screen of the television monitor 11 is included. Based on the output c from the scanning line counter 32, when a predetermined scanning line is reached, a counter control signal m is output, the width of the iris signal i is counted by the clock output j, and the output k is read to determine the scanning line. The corneal diameter can be obtained by converting the diameter of the iris image Pi on l.

The measurement operation procedure is as follows:
First, while aligning the ring image Pr with the target image Pa with good focus while pressing the measurement button (not shown), the light sources 5 and 6 are turned off and the iris diameter, that is, the cornea diameter is measured. While lit, the radius of curvature of the cornea is measured, but the procedure may be reversed. In addition, it is easier to perform the signal processing when the ring-shaped light source 5 is turned off when measuring the iris diameter.
Further, since the iris has a high reflectance with respect to infrared light, it is desirable to use visible light for external eye illumination.

As another measuring means, a television monitor 1
A ring-shaped corneal reflection image Pr by the light source 5 is projected on the surface 1, and this image Pr is generally represented by an ellipse. This ellipse can be calculated by calculating the intersection of the rings by using at least three scanning lines of the ring-shaped image Pr.
Thereby, the radius of curvature of the cornea in each radial direction can be calculated.

Furthermore, the microprocessor 27 may calculate the base curve of the contact lens based on the measurement results of the radius of curvature of the cornea and the diameter of the cornea, and output the result to the result display 28 and the printer 29.

[0015]

As described above, according to the optometry apparatus of the present invention, the optical system for projecting the anterior segment of the subject's eye on the television photographing means for observation and measurement is a telecentric optical system. The blur does not affect the measurement accuracy.

[Brief description of drawings]

FIG. 1 is an optical configuration diagram of a first embodiment.

FIG. 2 is a front view of a television monitor and a waveform diagram of a video signal of a specific scan line.

FIG. 3 is a block circuit configuration diagram.

FIG. 4 is a signal waveform diagram of a block circuit configuration diagram.

[Explanation of symbols]

 1 Objective Lens 2 Light Splitting Member 3 Aperture 4 Optical Sensor 5 Ring Light Source 6 Light Source 7 Alignment Target 11 Television Monitor 21, 36 Sample Value Hold Circuit 22 A / D Converter 25 RAM 26 ROM 27 Microprocessor 34, 35 Comparator 37 Single Stable multivibrator 38 Adder 39 Counter

Claims (3)

[Claims] 1. An illumination light source for observing an anterior segment of an eye to be examined,
A television photographing unit for observing the anterior segment of the eye and performing a predetermined measurement on the eye to be examined, and an optical system for projecting an anterior segment image on the television photographing unit, and the optical system is a telecentric system. An optometry device characterized by the above. 2. The optometry apparatus according to claim 1, wherein the predetermined measurement is a corneal diameter measurement. 3. The optometry apparatus according to claim 2, wherein a corneal shape measuring light source is provided around the optical axis of the optical system.